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BOMBDRPPING SIGHT FUR MRCRAFT. I

APPLicATlox man APR. 3. wxs.

- Paie-med Aug. 26, 1919,

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A. H. POLLEN AND H. F.1.ANDST/M). BOMB DROPVING SIGHT FR MRCRAFT.

APPLICATION man APR.3.1919.

Patented Aug. 26, 1919.

A. H, FOLLEN AND H. F. LAWDSTAD.

soms DROPPING sl-GHI Foa AIRCRAFT.

APPLICATEON FILED RFR. 3, |919. A) v A 9 I( l,31-,428. mememug. y? m13. l

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A.. H. PULLEN AND H. F. LANDSTAO.

Bom DHoPPmG SIGHT FOR AIRCRAFT.

APPLICATION FELED APR. 3.19l9.

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Il SHEETS-SHEET PatenedAug. 26,1919.

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.Emu Qoom APLlCATlUN FILED APR. 3. 1919,

'A. H. POLLEN AND H. F. LANDSTAD.

soms DaoPPmG SIGHT Foa MRCRAFT.

.Emu ooom Patentd ug. 2G, 1919.

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A. H. PULLEN ANU H. F. LANDSTAD.

80MB DROPPING SIGHY FOR AIRCRAFT.

APPLICATION FILED APR. 3. ISIS).`

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APPLICATION FILED APR. 3.1919.

Patented Aug. f .26', .1919.

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soma DBOPPING smHyFoa AIRCRAFT. APPLICATION FILED APH. 3. 1919.

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ARTHUR H. POLLEN, OF LONDON, AND H ALVOR F. LANDSTAD, OF YUK, ENGLAND.

Specification of Letters Patent. Patente@ Aug, 2, 1919.

Application led. April 3, 1918. Serial No. 287,329. i

To all whom. it may concern Be' it knownv that We,.ARTHUR HUNGER- Strand, London, YV. C2., andi-LiLvon loisiin STAD Laxos'ren, a subject of the King of Great Britain, residing at, Bishophill House, York7 Yorkshire, have invented certain new 'and useful Improvements in Bomb-Dropping .Sights for Aircraft, of which the fol lowing is a specification.

This invention relates to a sight for dropping bombs from aircraft, and depends for its action on the mechanical reproduction of a triangle of velocities. One vector of this triangle arranged parallel to the fore and aft lineoi' the aircraft represents in magnitude and direction speed through the air. The second vector which normallyT makes a small angle with the rst vector represents in inagnitiule and directionspced overland7 and 'the third rector represents in magnitude and direction the. speed of the wind. Y

lvl/'e proceed to descrihe. the invention with reference to the acconipanying;` draiiinn's in which- Figure l shows a. plan View of one 'torni of the si ghting device.

Fig. 2 shows an elevation of the saine `from "the Side.

i3 shows an elevation ol the saine from behind.

Fig'. shows the speed overland vector arm without an); Scale. inserted.

Fig'. 5 shows tour scales for use at ditlerent heights.

Fig. i shows a plan View of another torni ot' sighting.r device.

Fig 'T shows a plan View of the strip on which the scales are. marked.

Fig'. S is a side elevation of the rollers on which the scalo strip is mounted.

Fig. 9 shows another modifi lation oit the sighting' device..

Fig. .l is a plan ot still another modification ot' the sighting device.

Fig'. ll is a side ele ation of the same.

Fic'. l: is an end elevation ot the sanne..A

Fig. 'l2 a development. ot the. drinn for setting. speer-l overland.

ln one h mounted l n.1 ot our invention the sight is a rectangular trame, which is l'orinefi t: a the horizontal bars l, l see Figs. 1,:2 and 3 and the end pieces '2, 2. This i plan view oit a speed recorder.

frame is leveled up and fixed to the aeroplane body with bolts 3 so that it rests on three bosses at the side of the aeroplane body. The sighting device which can be hooked on the upper bar l and is guided by the lon-'er bar, and can he horizontally set along these hars in order to suit the, pilots convenience. Clamps l, hold the sighting device in position on the hars with sutlicient friction, therefore no locking device is needed.

The rst vector or speed through the air Vector (which can be read on an anoniemeter) is set up parallel to the fore and att line. of the aircraft by moving' a block 2S in a horizontal guide 29 toward or away from the intersection .el of a .tixcd pair ot cross- Wires gj and z carried by a swinging sighting* arrn 13 to be 'more particularly described hereinafter.

These. crosswircs, the point ot' intersecf tion 21v of which crossivircs constitutes a pointer.,E are arranged verticali;v beneath the normal position of an egrepiece i5 with said' pointer in vertical coincidence with the eri piece, andthe latter is convenient-ly fixed so that the, airinan can lean over to the. side. and lool; vertically down through it.' at the ground. The block Q8 carries a ialcriun Aw on which pivots the third vector of the tri angle namely the arm 12 representing speed and direction ot Wind. In Fig. l, the arm l2 is shown in its ii-'orking position hut. in Figs. and the arm l2, block and the guide 29 are shown 'folded up into a vertical posit-ion about the hinqe 3l by which the aforesaid parts are attached to the inain body ot the. sighting device. rthis arrangement reduces the danger ot the arm l2 hecoining damaged when not in use. rthe scale 30 or" speed through the air is'coni'eniently arranged :it lOniiles per honi' to thev inch, so that if the speed through air is miles per hour, the distance from el, to the tulcrnin @o of the third or Wind speed vector ot the triangle will be f5 inches. The sett-ing' for any given speed through the air easily accomplished by a. lninrled head 5 on a screw which nioi'cs the block 'in. 'the horizontal guide. 529.

The second or speed overland rector" is represented. hy the ina-in swingingerin lil hich mounted at its inner end to swing annind an exis -oincident with the. point ol' icc either side of the fore and att line of the aircraft.` The arm is provided with a oentral track Wire constituted by the Wire y before alluded to, which Wire is fixed at its -opposite ends to the ends of a longitudinal The arm without any scale is shown inl Fig. e and 'four scales tor different heights of flight are shown in Fig.

It will be noticed that the graduations on the second vector representing speed overland are not in miles per hour but in seconds of time. The reason for this ivill be apparent later.

'We now proceed to describe the method of obtaining the vector speed overland. In the first place, it is easy to so set. the arm 13 that objects viewed through the eyepiece 6 appear to follow down the track wire y.

lVhen this is done, the direction of the arm corresponds with the direction ot Hight overland. To obtain theinagiiitude or" this vector, the height at which the aircratt is flying is ii'st noted and a corresponding scale is chosen. The scale slips into a pocket 17 at one end and a catch 18 holds it in place at the other end. This scale can easily be replaced by another scale--a one-hand motion. i

The pilot Watches an object through the eyepiece 6 and swings the horizontal arm 13 in line with the track of the aeroplane by knob 2-1, that. is he swings the arm 13 so that the object he is Watching through the eyepiece G, will pass along the track line y, and at the same time aiming the flight so that the contiiuiation of the track line g/ must be pointing iii the direction or" the object to be bombed. The horizontal arm 13 is then ready set in line with the A"course overland ot the aeroplane, and the observation of speed overland can noiv take place.

A slider 19 is mounted in guides fixed iinderneath the horizontal arm 1B iwhich c be set br' rack and pinion by knob To this slider is fixed a wire a' which. at it right hand end, serves as a setting pointer with the scale 20. and at its lett hand end serves, as a pointer with the division line 2G, 253i marl-:cd tull time 1;-,

This slider ie now set outward along the horizontal arm '13 by the knob 25 so that the pointer a' at its left hand end in line with the division line '26 marked full time. In this position the line joining the crossivires' 7 in the eyepiece 6 and the wire m forms an angle 30 with the verticalline through the eyepiece and the intersection el of the Wires y and z. The eyepiece is placed in its normal position and an object is observed passing along the track liney. At the moment the object arrives at the position n3, the pilot .starts a stop-Watch conveniently providedv with a, iexible trigger motion; (the Watch being most conveniently fixed in a holder on the dash-board). He

follows the objecty until it is vertically below the eyepiecehthat is at 21, and stops the Watch with a second pull on the trigger. It will be observed on inspecting the scales shown in Fig. 1 and Fig; 5 that the scales carry on their lett hand sides graduatious in seconds. "luis the scale for 1000 feet 'is graduated from 16 to L10 seconds. VThese graduations are calculated to give the speed overland (at the scale of 10 lmiles per hour per inch) for the time of flight over a distance on the ground subtending 30 at the. height of liglit. Consequently' if the time indicated by the stop-Watch were seconds and the height 4000 feet, the terminal ot` the speed overland vector will coincide with the graduation Q2 on the 1000 toet scale. All that is necessary to complete the triangle or' vector velocities is to rotate the wind `vector arm 12 around the pivot fw until its edge intersects-the track line y at the graduation This is the position-shown in the drawing.

For the and time positions it these are used instead ot' the fulltime position the time observed must be multiplied by two or four.

ll'hen the arm 12 has been set as described it will represent the direction of the Wind and also its .speed and the arm 12 is therefore graduated to the same scale ot 10 miles per hour per inch and the value of the wind velocity is read directly against the track wire y.

'We now have all the data for setting the sight, it will be noticed that each scale has a graduation on its right hand side also 1n seconds. These are determined so that. with a speed overland represented as above of 22 seconds say, the crossivire a: niust be placed in coincidence with the right hand graduation so as to act as a correct 'foresight tor dropping the bomb. In making the calculations for these. graduations, the various factors of hei ,'ht, speed overland and C u ance of the air tor the particular bomb chosen are talfeii into account. 'lt another fyi e ot bomb is used, the scale is shifted J lv on its supporting arm as shown hi* the Nadu-ations 2'( on. the scales at the right. hand lowercorner. A similar correction is applied to the eyepiece by knob 9 with 1,314,428 y L n g3' graduations 22 or 23 according to the per`- ticulnr type of bomb employed.

Both these corrections are vinode before leaving the ground.

It now ienniins' to explain how the correction for the eii'ect ot the Wind on the bomb is made. v

The eyepiece 6 With crosslines i is mounted at the top of the instrument in such nunincr that the eyepiece can be set eccentric with regard to thet'riune ring S by o. knob 9 by ineens of zi screw action.

The amount of eccentricit may be read oilon the graduzitions 22 an 23 on knob 9.

"1e rinfrv i iA e e 'e )ie e stern is ll ,D 11 nwhicl th y; c

mounted rides on the frame ring 8 and can slide around sanne. These two move.

lt will be noticed that in the constructions Shown in Figs; 1 to 5 the speed overland vector is more ndnptnhle 'tor being operated outwardl that is. to the-lett. It may therefore be usctui to carry a sight ou each side ot the nircrnit, one for use when the wind is 'from the right und the other when the Wind is troni the loft.

in Fig. 9 :i modied construction ot the sighting device is shown which obvietes the necessity for carrying a sighting( device on each side ot' the. aircraft. 4The main difierence between this` construction and that first described resides in the support ot the tub cruni ir. It vvill be seen troni Fiff. 9 that in thisA form of the device the speed through the nir is set up on n ldidine,l bnr 32 sliding in a guide opernted b v the linurled head 5.

The sliding bnr T32 carries a circular track 34 in which .slides n slider 85 carrying the i'zulinl nrin fifi :it whose extremity w (Which nlvrnys coincides with the center of the circulnr trncl; Si) is pivoted the vrind vector arm Si'. large opening is provided through which the objects on the ground cnn ne viewed :1nd it will be seen that iu this construction the speed overlnnd vector 13 und the wind vector 12 can he set to either side of the tore :ind 'ift line Should the nvintor zitter releasing his bomb desire to return on n diiierent course in order to tire :mother bomb it is not neces- Amuv to :renin tolte observations for .speed m'crlnud, nlrhough the speed overlandv `will on the second ocvnsiou diticr from that on the firstoccnsiiin. because he con reset his sigilu cf'uzilly ive-.ll Atroni the speed of Wind which nung; he nssunied unchanged. Hc

therefore proceeds as 'follows :-Arn1' 13 is set so that the track wire y coincides with the- 'will canse the erin l2 to lintersect the track wire at soine graduation on these-rile., and if the foresight :v is set to the sinne graduation on scale 20 the foresight will be correctly set for the new course. The arm 21 is then set parallel to the new position of arm 12 and the sight is now ready for releasing another bomb es soon as the objective cornes into line of vision on the new course.

We may, if desired, introduce n modication inthis system in which the speed overland which as before was obtained in miles per hour is set up by inc-.ms of the Wind vector in the scaie inserted in :irm in miles per hour in Fig. 6.

With the arrangement it is not necessary to change the scales inserted in firm 1.3 tor various heights but on` the other hnud the bomb dropping scale 2() in Fig. 1 must be changed for varying heights.

Vile accordingly provide :i series oi scales shown in Fig. 7 for various heights printed transversely on n. long; strip ot' paper, any

one of which can be brought into operative position by handle SG which rotates roller SY on which the strip is mounted. These scales are grndunteil both in time .find in height and :in index S8 in circle S) serves to set-the time as indicated by the stop Wat/chend nt the seine time serves to indicate the speed in miles per hour overland when 'the proper altitude scalo is turned into its operative position by hnndlc- SP.

The index SS is moved by the innidlc En) 'by revolt :ind pinion motion and carries Jue foresight a; with it.. The fore` ut. so set will be in the right position for dropping the. bomb. The speed in miles per hour o`ntained `from the scnle :it once gives the position at which the Wind vector must be set to intersect the miles per hour scale inserted in erin 1?, :uid thus indicate the di rection of the wind.

The advantages of this construction :ire

thut you set up time of l'iiflht over the :ingle of 300 on the ground und obtain speed in miles per hour directly und it the :xiinde is not changed the foresight correctly Set.

If however, the altitude is change-1d: being assumed that the speed ovcrhind remeins vconztznit :ill thnt is necessary is to Wind the strip Q1 so :is to present n scnle correspondii'igr to the new altitude :ind it the index line is ser to the speed (inert-nui on this new 'sc-:de this will be the new position tor the foresight.

ive non' proceed to descrilnnnother :nodiiicntion ot the nliore siglitinrr mechanism which is designed so thnt the grrnduntions La! for speed overland for ull heights are set out on one scale drinn 5 therefore 1r the pilot wishes to change his altitude suddenly, hisV speed overland for the new altitude can be easily re-set by ineens hereinafter described. The principle of the sight remains the saine, the vector triangle formed by the three vectors speed through air speed overland and speed of Wind*`7 is unchanged but the method of obtaining Speed overland is changed in that instead of timing the Hight of the aircraft over a distance subtending 303 at the aircraft, the flight is timed over adeinite distance on the ground say lrd ot a mile.

Referring to Figs. 10, 1l and 12 as before the speed through the air is set upby shifting the block Q8 parallel to the foie and aft line ol" the aircraft by means of the knob 5 mounted on the screw l2 which enreges with a nut fast on the blocli 2S. The

block 2S as before carries a fidcruin 'T5 around which the Wind vector arin l2 can rot-ate in a horizontal plane so that it lies over and intersects the speed overland vector arm 13 pivoted at z, which point is as before the origin ot the speed through the en' unc speed overland vectors. In order to adapt the sight to the 'modified method of determining speed overland it has been seperated from the vector triangle out the arm lll und the Whole ol" 'the rest or the sight pivot. around the axis 21h, As before there is an eyepiece (3 provided with crosswires 7 carried on a ring 8 capable or" being rot-ited around the ring S and of beingl set eccentric to the ring by the lcn'ob 9 by means ot u. screw action. The ring 8 can swing about centers l0, 40, so that the yaxis of swing is horizontal and perpendicular to the speed overland vector 12?. The ring carries a depending arni. 3D which arm oarries at its lower end the fore sight in the form of a. loop fll with croeswires. As the ring S aud arm 39 are swung about the axis l0, l0 the line of sight Will follow the course overland of the aircraft. A back stop 3S is provided which determines the position when the line of sight is vertical.

It will be easily seen that at any given height of ilight there is a particular angle 1which will be subtendcd at the aircraft by lrd-ot' a milo of grouiul, und the n'iethod o determining speed overland is to set the arm Iii) foi-Ward ot the `vertical by 'this angle and to observe the. time interval between the instants at which an object on the ground crosses the line of sight in this position and again cro s the line of sieht when the latmoved hach' to the stop 25 in the interval. In order to be :phi-- to Het the erin conveuientljT to this forv-.ziwi angle, the arm is driven `troni u. handle l f.- currying geur wheel 5 meshwheel 1t-t2 on. .shaft carrying Worm 48 engaging with sector i9 fixed to the ring 8 and in order that the angle may be at once determined through which the arm mustfbe moved for a given height in order to ascertain speed overland, the handle shaft l-l: also carries a gear Wheel 50 meshing with gear Wheel 5l on shaft 52 carrying a drum 53. The drum is graduated around one .end (as shown developed in Fig. 13) in heights above the ground and when the handle d3 is rotated to bring the desired height graduation against a pointer, the arni will be set to subtend a distance oi rd ot D. mile on the ground :it that height between the forward and backward position of the line of sight. Thus in order to obtain the Speed overland an objectis viewed .through e. line formed by thecrossivircs in the front and rear sighting loops, and at that instant the speed recorda-ir,` or stopf Watch (see Fig. lil) is set going, and the arm 3S) is gradually moved into the vertical position, the object aimed :it being kept within the area of the sighting loopsand when the object viewed passes the crossvfircs the speed recorder stoppedand the pointer 18 will indicate a figure on the card 19. It the minimum speed of 20 miles per hour is assumed and the watch makes one revolu tion while arm swings from one position to the other, that is u distance of -lrd of a ,i

inile on the ground 'then the pointer 19 must make one revolution in one ininute which equals a speed ot' 2O miles per hour; a halt' revolution of pointer will be equivalent to -lO miles per hour, a quarter revolution equals SO niiles per hour and so on; therefore the pointer li will directly indicate the speed overland of the aircraft.

The speed overl-nud, could, if desired he read oil' in seconds ot time; the graduations on the drum would then be graduated in seconds of time, and the figure Which is now 2O would become 60,40 would become 30, SO would become 15 and so on.

Having thus obtained the speed overland the foresight is set to the required angle by rotating the handle 42S until the speed overland is indicated against the pointer 5S the pointer having already been set to the height by ineens ot the pointer 55 against the height as shown on graduated scale 5l. lt will be seen that the graduations on thc drinn ere really curvesI representing the pci-- sitious of the drinn for a given overland speed at various heights, one coordinate he ing angular position oit drum and the other height.

The magnitude and direction ofthe Wind vector is obtained 'from the saine linac 55e before h v setting up speed through no, lmob' thus positioning :Fulcrum ,75, h g: ting up speed overland b v lmoh l means ogt :i sco-,w which moves :i nut .3T gli the .speed overland arm which nut eng lli) e slot in the Wind vector arm which is piv- In this Way the magnitude of direction ot' the Wind, the ring 8 is rotated in the ring ll to set up direction of Wind on scale 6l against pointer 62 andy the backsight is set by rotating the druxn 63 to the height of the aircraft and moving the pointer to the observed speed of wind. The becksight und foresight are new both set and if the bomb is released when the ob` jeetive comes intoline of sight a hit should result.

The curves of graduations on the drums and 613 are calculated to give the necessary direction of the line of sight to obtain e. hit taking into account the resistance of the nir to the normal bomb. Another type of bomb merely requires :i fresh pair of drums to be fitted.

Vith both types' of bomb sight o pair of cross levels ere fitted to the aircraft to en- 'able it to be iiown on an even heel.

It will be easily vseen that when dying over 'see it is ditlicult to obtain e. fixed object on which to sight. ,A

rfhe observer drops lent which produces n visible eect on hitting the Water such es u light or e column of smoke. This 'bomb will hit the Water o. certain amount -estern of the aircraft at the moment of impact in a. certain direction depending on the height of flight, the speed of the Wind and the course over Water.

ln order to obtain speed over Water by this method the observer must fly either with or against' the Wind so es to have no drift and ut a known speed say 60 miles per hour.

Under these conditions at n given height :ind speed the aircraft will be at the moment oi' impact ahead of the place of impact by e definite angle ce.'

As all obser 'ations here to be mede ostern insteud of ahead, n foresight position 30 nstern of vthe vertical through the plane is fitted in the urm 13.

The procedure for obtaining speed over Water is es {chewy- The observer drops4 e bomb or its equivadirecton oi the drittless speed of the aircraft through the nir, the speed of the Wind can be obtained by silbtructing the speed through the air from the speed over seu determined from the observation of the bomb.

Te have now determined the direction and speed ofthe Wind und the aviator con conichently put his machine in the desired course und by setting his wind .vector to the direction of the windV und 'arranging that the speed over lend vector shall out the wind Vector ot the point indicuting the known speed of the Wind, the aviator can determine speed overland or see on his new course. I

The method of determining When to re-` lease the'boin'b is as before.

lVhat We claim is 1. In a. sighting device for nii-crafts, the combination of a supporting frame, e sightingurni pivoted to seid freine and having grnduutions for uee at u certain height to indiente (lider-ent speeds overland, u. .slide movable to and from the exis of the erin to indicate the speed through the air, ande Second arm pivoted to the slide and adapted to be set et the graduation onrthe sighting erm representing the particular overland speed, said second arm beingr provided with gri-duatone adapted to be reed in connection Awith those on the sighting arm end representing the speed of the Wind.

2. in u sighting device for uircroi'ts, the i combination of n supporting frame, a.

sighting erin 'pivoted to said frame and hiivingv u truck line along which the pilot may sight on object below. said sighting arm udnpted to be set to represent the speed overland vector, e slide moi'- able to and fron'. the axis of the sighting arm und adapted to he set to represent the speed through the niivector. und an erm pii'oted to said slide and adopted to be set with reference to said first mentioned urn'i to represent the speed und direction of Wind Vector.

3. In n sighting;r device for nircruts. the combination of u supportingV treme. :i .sighting erm, pivoted to said frame und l'im ifig u truck line along which the pilot niet* sight un objectbeloW. said sighting arm having g'rncluutione calculated with reference to the Speed through the uir. und the. strength of the Wind ut :L given height. to represent the speed orcrlund. u second urmhaving graduotions adapted to he rc: d in connect` n with the linduotions*on the sighting urm. und calculated with reference to the spr-ed through the nir und .speed ovcrlzu'xd. to represent the strength of thc Wind. :ind :i slide worrying said eci-ond :n'xu :ind adapted to be sei toindic-xtc the spe-d through :he oir.

L lin :i sighting device for uircru the comido-dion of u supporting nnoe. Mehting urin pivoted to said frume- -und having n.

vertical coincidence with the eye-piece, whereby the speed overland may be determmed, sold second' pomter bemg movable lengthwise of the track line and adapted to be read in connection with JUne second set of gzaduultlon's on the s1ght1ng arm to serve as u oreslght 1n droppmg the bomb, and sold second zum being adapted to be setwth refl2. In a sighting device for aire-rafts, the

combination o' a supporting frame, a sighting arm pwoted thereto to swing horlzontally and having a track line along which the pot may slght 2m obgeeb below by swinging the arm horzontaly, an eyepiece `above the trackl line, a pointer associated with the teck line in vertical coincidence with the eye-piece, and e. second pointer essocated with the track line to serve as a foresight in taking observations to detelmine the speedl overland, said second pointer being movzxbe to :L different position to se've as alforesight in dropping the bomb.

In testimony whereof We have hereunto setour hands in presence of two subscribing witnesses.

ARTE-IUE H. POLLEN. HALVOB F. LANJDSTi D. 

